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At least 1,585 records · Page 88

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NASA NTRS1976

Optical noise suppression device and method

A device and method is disclosed for suppression of optical noise in an optical spatial filtering system using highly coherent light. In the disclosed embodiment, input photographic film to be processed in the system, and output photographic film to be exposed, are each mounted on lateral translation devices. During application of the coherent light for exposure of the output film, the two translation devices are moved in synchronism by a motor-driven gear and linkage assembly. The ratio of the resulting output film translation to the input film translation is equal to the magnification of the optical data processing system. The noise pattern associated with the lenses and other elements in the optical processing system remains stationary while the image-producing light moves laterally through the pattern with the output film, thus averaging out the noise effect at the output film.

Horner, J. L.↗

NASA NTRS1976

Magnetoresistance and noise properties of chevron stretcher detectors for field access bubble domain devices

Experiments were devised to study the angular variation of the resistance and noise properties of one- and two-level chevron stretcher magnetoresistive detectors for use in field access bubble memory devices. All measurements, made with an electronic system, were performed on glass or garnet samples upon which 1 micron of SiO2 was sputter-deposited, followed by 4000 A of Permalloy for the 28-micron-period devices and 0.8 microns of SiO2, followed by 3000 A of Permalloy for the 20-micron-period devices. The geometrical and drive-state dependence of the zero-state noise were studied, as was its frequency dependence. It is found that both types of detectors operate primarily in the amplitude-shift mode for drive fields of interest and that the presence of a bubble in a detector causes a magnetoresistance change equal to that produced by increasing the in-plane drive field about 8 Oe in the absence of a bubble.

George, P. K.↗

NASA NTRS1976

A technique for optimizing the design of power semiconductor devices

A technique is described that provides a basis for predicting whether any device design change will improve or degrade the unavoidable trade-off that must be made between the conduction loss and the turn-off speed of fast-switching high-power thyristors. The technique makes use of a previously reported method by which, for a given design, this trade-off was determined for a wide range of carrier lifetimes. It is shown that by extending this technique, one can predict how other design variables affect this trade-off. The results show that for relatively slow devices the design can be changed to decrease the current gains to improve the turn-off time without significantly degrading the losses. On the other hand, for devices having fast turn-off times design changes can be made to increase the current gain to decrease the losses without a proportionate increase in the turn-off time. Physical explanations for these results are proposed.

Schlegel, E. S.↗

NASA NTRS1976

Prediction and measurement of radiation damage to CMOS devices on board spacecraft

The CMOS Radiation Effects Measurement (CREM) experiment is presently being flown on the Explorer-55. The purpose of the experiment is to evaluate device performance in the actual space radiation environment and to correlate the respective measurements to on-the-ground laboratory irradiation results. The experiment contains an assembly of C-MOS and P-MOS devices shielded in front by flat slabs of aluminum and by a practically infinite shield in the back. Predictions of radiation damage to C-MOS devices are based on standard environment models and computational techniques. A comparison of the shifts in CMOS threshold potentials, that is, those measured in space to those obtained from the on-the-ground simulation experiment with Co-60, indicates that the measured space damage is smaller than predicted by about a factor of 2-3 for thin shields, but agrees well with predictions for thicker shields.

Cliff, R. A.↗

NASA NTRS1976

Percutaneous connector device

A device is reported for facilitating the passage of electrical signals from an external source through the skin of a patient to internal portions of the body such as muscles and nerves. The connector device includes a bio-compatible shell having an enlarged disk shaped portion for being implanted below the skin of the patient. The shell has a first and second electrically conductive post carried therein upon which a plug can be readily connected and disconnected. A modified form of the invention utilizes a unipolar connector that is adapted to be plugged into a shell implanted below the skin of a patient. Both of the connector devices are designed to be separated when a predetermined force is applied. This prevents excessive force from being applied to the implanted bio-compatible shell.

Parsons, W. E.↗

NASA NTRS1976

Two-dimensional radiant energy array computers and computing devices

Two dimensional digital computers and computer devices operate in parallel on rectangular arrays of digital radiant energy optical signal elements which are arranged in ordered rows and columns. Logic gate devices receive two input arrays and provide an output array having digital states dependent only on the digital states of the signal elements of the two input arrays at corresponding row and column positions. The logic devices include an array of photoconductors responsive to at least one of the input arrays for either selectively accelerating electrons to a phosphor output surface, applying potentials to an electroluminescent output layer, exciting an array of discrete radiant energy sources, or exciting a liquid crystal to influence crystal transparency or reflectivity.

Schaefer, D. H.↗

NASA NTRS1977

Combined docking and grasping device

A combined docking and grasping device for use with a manipulator arm on a docking vehicle and the like for mechanically connecting a docking vehicle with an orbital payload having a receptacle for receiving the device is described. The device includes a pair of opposing jaw members having opposing serrated surfaces for grasping an object and a triangular cam portion on an outer surface for insertion and interlocking with an orbital payload.

Burch, J. L.↗

NASA NTRS1977

Process for preparing liquid metal electrical contact device

The parts of an electrical contact device are treated by sputter etching to remove the parent metal oxide. Prior to exposure of the electrodes to any oxygen, a sacrificial metal is sputter deposited on the parts. Preferably this sacrificial metal is one that oxidizes slowly and is readily dissolved by the liquid metal. The sacrificial metal may then be removed from unwanted areas. The remainder of the ring and the probe to be wet by the liquid metal are submerged in the liquid metal or the liquid metal is flushed over these areas, preferably while they are being slightly abraded, unitl all the sacrificial material on these portions is wet by the liquid metal. In doing so the liquid metal dissolves the sacrificial metal and permanently wets the parent metal. Preferred materials used in the process and for the electrodes of electrical contact devices are high purity (99.0%) nickel or AISI type 304 stainless steel for the electrical contact devices, gallium as the liquid metal, and gold as the sacrificial material.

Lovell, R. R.↗

NASA NTRS1977

Corneal seal device

A corneal seal device is provided which, when placed in an incision in the eye, permits the insertion of a surgical tool or instrument through the device into the eye. The device includes a seal chamber which opens into a tube which is adapted to be sutured to the eye and serves as an entry passage for a tool. A sealable aperture in the chamber permits passage of the tool through the chamber into the tube and hence into the eye. The chamber includes inlet ports adapted to be connected to a regulated source of irrigation fluid which provides a safe intraocular pressure.

Baehr, E. F.↗

NASA NTRS1977

Lower body negative pressure device

The Lower Body Negative Pressure Device was used, in the space environment, to stress the astronaut's cardiovascular system, to determine the extent and time course of his cardiovascular deconditioning and to determine whether in-flight data from experiment M092, Lower Body Negative Pressure, would be useful in predicting postflight status of orthostatic tolerance. The lower portion of the subject's body was enclosed in this device for the purpose of applying regulated and controlled negative pressure. A description is given of the device.

Nolte, R. W.↗

NASA NTRS1976

Prediction and measurement of radiation damage to CMOS devices on board spacecraft

The CMOS Radiation Effects Measurement (CREM) experiment is presently being flown on the Explorer-55, to evaluate device performance in the actual space radiation environment and to correlate the respective measurements to on-the-ground laboratory irradiation results. The experiment contains an assembly of CMOS and P-MOS devices shielded in front over 2 pi steradian by flat slabs of aluminum of 40, 80, 150, and 300 mils (1.02, 2.04, 3.81, and 7.62 mm) thicknesses, and by a practically infinite shield in the back. Initial results from the CREM experiment are reported. Predictions of radiation damage to CMOS devices are based on standard environment models and computational techniques. Measured space damage is smaller than predicted by about a factor of 2-3 for thin shields but agrees well with predictions for thicker shields. It is not clear at this time how the trapped particle environment models or the computational methods should be modified in order to achieve better agreement between experimental results and predicted damage curves.

Cliff, R. A.↗

NASA NTRS1977

The charge-flow transistor - A new MOS device

A new device, the charge-flow transistor (CFT), has been developed to achieve integrated MOS compatibility in sensor applications, such as gas, humidity, and fire detection, where one is interested in monitoring the transverse resistance of a thin film. The resistive material is incorporated into the gate structure of the CFT in such a way that there is a time delay between the application of the gate-to-source voltage and the appearance of a complete channel. This time delay depends on the resistivity of the thin film. A theory of device operation is presented, together with experimental results on the first CFT's. These results confirm the principles of operation, and demonstrate the utility of the CFT for making fully integrated sensing devices.

Senturia, S. D.↗

NASA NTRS1976

Testing electroexplosive devices by programmed pulsing techniques

A novel method for testing electroexplosive devices is proposed wherein capacitor discharge pulses, with increasing energy in a step-wise fashion, are delivered to the device under test. The size of the energy increment can be programmed so that firing takes place after many, or after only a few, steps. The testing cycle is automatically terminated upon firing. An energy-firing contour relating the energy required to the programmed step size describes the single-pulse firing energy and the possible sensitization or desensitization of the explosive device.

Rosenthal, L. A.↗

NASA NTRS1977

Mechanical energy storage device for hip disarticulation

An artificial leg including a trunk socket, a thigh section hingedly coupled to the trunk socket, a leg section hingedly coupled to the thigh section and a foot section hingedly coupled to the leg section is outlined. A mechanical energy storage device is operatively associated with the artificial leg for storage and release of energy during the normal walking stride of the user. Energy is stored in the mechanical energy storage device during a weight-bearing phase of the walking stride when the user's weight is on the artificial leg. Energy is released during a phase of the normal walking stride, when the user's weight is removed from the artificial leg. The stored energy is released from the energy storage device to pivot the thigh section forwardly about the hinged coupling to the trunk socket.

Vallotton, W. C.↗

NASA NTRS1977

A design handbook for phase change thermal control and energy storage devices

Comprehensive survey is given of the thermal aspects of phase change material devices. Fundamental mechanisms of heat transfer within the phase change device are discussed. Performance in zero-g and one-g fields are examined as it relates to such a device. Computer models for phase change materials, with metal fillers, undergoing conductive and convective processes are detailed. Using these models, extensive parametric data are presented for a hypothetical configuration with a rectangular phase change housing, using straight fins as the filler, and paraffin as the phase change material. These data are generated over a range of realistic sizes, material properties, and thermal boundary conditions. A number of illustrative examples are given to demonstrate use of the parametric data. Also, a complete listing of phase change material property data are reproduced herein as an aid to the reader.

Humphries, W. R.↗

NASA NTRS1978

The study of surface acoustic wave charge transfer device

A surface acoustic wave-charge transfer device, consisting of an n-type silicon substrate, a thermally grown silicon dioxide layer, and a sputtered film of piezoelectric zinc oxide is proposed as a means of circumventing problems associated with charge-coupled device (CCD) applications in memory, signal processing, and imaging. The proposed device creates traveling longitudinal electric fields in the silicon and replaces the multiphase clocks in CCD's. The traveling electric fields create potential wells which carry along charges stored there. These charges may be injected into the wells by light or by using a p-n junction as in conventional CCD's.

Papanicolaou, N.↗

NASA NTRS1977

Cartridge firing device designed for attachment, release and ejection of a satellite

The device functions were performed by a one-piece unit with resulting performances which were of interest regarding the satellite attachment and the accuracies of the path and velocity during separation and ejection. A gain in weight may be obtained relative to the conventional device used, i.e. maintenance belt, belt unlocking device, pusher spring, and cartridge fired pusher.

Pierron, L.↗

NASA NTRS1978

Pattern classification using Charge Transfer Devices

The potential uses of Charge Transfer Devices (CTDs) in pattern classification operations are explored. The needs for a hardware-based pattern classifier are established, and a matrix multiplication subsystem based upon a sum of products CTD is presented. An evaluation process for sum of products devices (particularly analog-analog correlators) is developed, and the feasibility of employing a particular device in a pattern classifier is determined. Finally, the possible impact of future trends in technology is considered.

Snyder, W. E.↗